High-pressure metamorphism in the Cycladic Blueschist Belt, Greece

This DFG-funded project aims at Rb-Sr multimineral isotopic dating of high-pressure metamorphism of an ophiolitic melange and a shelf sequence in its footwall, on the islands of Syros and Sifnos (Cycladic Blueschist Belt, Greece). On Sifnos, the shelf sequence shows well preserved blueschist facies assemblages in the north of this island (blueschist unit), whereas in the south high-pressure rocks experienced intense greenschist facies retrogression (greenschist unit). These differing metamorphic evolutions are explained either by differential exhumation, by localized and selective fluid infiltration, or by a thermal pulse at the base of the greenschist unit. Surprisingly, pressure-temperature paths of both units are very similar. Fission track data may help to distinguish between the different interpretations. We are working on new approaches for isotopic dating of high pressure rocks and of retrogressive stages. Results will contribute to a better understanding of the exhumation of high-pressure rocks in forearc settings.

 

• Contact:  Dr. Johannes Glodny